Erecting eyepiece with variable magnification



Patented Dec. 15, 1953 ERECTING EYEPIECE WITH VARIABLE EEAGNIFICATIQNGunther F. E. Locck,

North Troy, N. Y., assignor to W. 85 L. E. Gurley, Troy, N. 55., acorporation of New York Application August 27, 1951, Serial No. 243,811

(Cl. S8-32) l Claims. 1 This invention relates to oculars for variablemagnification telescopes.

Accord to the invention telescope is proided wh xed objective lenssystem and xed erecting Associated with e lens systems is an ocularcomprising at not two enses which movable elatively to said cb'ectiveand erecting lens eye ns to zer. Movement of Thus on so that optimum heachieved. produced at the focal ..g lens system is dependent on lacemontand, of the aperture in diaphragm.

A further advantage realized by a lens system invention is that theactual 0:. view is some for the various magnification of the ocular.

a preferred embodiment of the invention will he described ing referenceto the accompanying drawing, in which:

Figure 1 fragmentary section of the telescope showing the erecting lenssystem and the ocular lens system.

Figure 2 i a side elevation of the adjusting sleeve or the ocularlenses.

Figure 3 diagrammatic representation of the lens sys the completetelescope.

Statements of direction refer to parts position-ed as Figure 1.

As indicated in Figure 3, the telescope lens system includes anobjective system comprising the objective i, the negative ens l2 and. agraticule it. These are all fixed in the tube 22 of the telescopeconventional means. The tube 22 of the telescope appears in Figure l,but the objective end thereof is br-- zen away to shorten Figure l andthus permit the use of a large scale. No novelty here claimed for themounting of the objective and hence illustration of these conventionaldetails is deemed to be unnecessary.

The erecting lens system comprises the lens i l, cli Lragm l5, lens lensl? and diaphragm i8 god in the order stated, which is to say thataphragm iii is located between the lenses is and the diaphragm is at thefocal the erecting system. The parts i i to it are .-xecl1y mounted asparts of a subassembly hereinafter described in detail. That sub-assem-'2 is hly is fixedly mounted in the telescope tube, provision being madefor adjustment or the subassembly in the direction of the axis of thetube at the time the sub-assembly is mounted.

The ocular as illustrated comprises two lenses I and 2! and an adjustingmeans common to the two and arranged to move them at chosen rate-srelatively to each other and to the erecting lens system. The motions ofthe two lenses it and 25 are so coordinated that the anterior focalplane of the oculais at all times coincident with the posterior focalplane of the erecting lens system.

The desired result can be attained very simply mounting in the end ofthe telescope tube an assembly which includes the erecting sub-assembly,in fixed relation to the tube, two telescoping which carry respectiveocular lenses, and e. eled ring and connected adjusting cam sleevemechanically related to said telescoping tubes. This structure is shownin Figure l.

A bushing 23 is threaded at is into the eyepiece end of tube 22, and hasa flange 25 which seats against the end of the tube assuring firmpositioning. At the left end it has a bore which supports a fixed guidesleeve at the right end it has a large counterbore through and beyond.which guide sleeve 26 extends. Sleeve is fixed in bushing 2.3 by a setscrew 2?.

A tubular cam 23 is rotatable on sleeve and fits an annular socket inadjusting ring with which it is permanently connected. Solder asatisfactory connection. The ring has a flange 3i which overhangs theright end of bushing 23. 29 is confined between the end of bushing 23and a ring-nut threaded at 33 on the end of sleeve 26. Cam 28 connectedring 29 are thus swiveled on guide sleeve iii; 1'. e. they can rotatetogether thereon but are r strained against axial displacement in eitherdirection.

Cam 28 is shown clearly in Figure 2 and has two generally helical slots34 and 35 of opposite pitch. These are not necessarily identical, nor iseither necessarily a true helix. Their form will be explained later.

The cam followers are cylindrical pins 35 and 3? which extend through alongitudinal slot 38 in guide sleeve 26. Pin 3? extends radially fromthe outer one 39 and pin 38 from the inner one ii of two coaxialtelescoping tubes, the outer of which is slidahle in guide sleeve andthe inner of which is guided in the outer. The slot 38 confines both ofthe cam followers and so inhibits rotary motion of tubes 39 and ll Tubell carries an integral mount l2 for lens 19. A mount 53 for lens 2| isthreaded to the end of the outer tube 39. Turning of ring 29 in one orthe other direction will cause lenses l9 and 2! to approach and recedetoward and away from one another. The character of motion of each is afunction of the design of cam slots 34 and 35 and these motions arecoordinated. I

The erecting sub-assembly is fixed in the left hand end of guide tube 26by set screw it which engages the large cylindrical portion 45 of atubular housing whose small cylindrical portion 46 extends to the rightwithin, but clear of, tube El. Set screw id permits adjustment of thehousing d5, 56 in axial directions at the time of assembly.

A cylindrical shell ii makes a snug fit in portion 15 carries thediaphragm 16. At its opposite ends it is threaded to receive mounts iand 49 for the lenses i4 and Hi. At its remote (right hand) end, portion4% is counterbored to receive an assembly comprising mount 5! for lensif and the diaphragm it, which is threaded at 52 to mount 6!.

The forms of cam slots and 35 are determined according to the opticalcharacteristics of lenses i9 and which, respectively, they adjust asring is turned on tube 22. The cam slots are such that the lenses l9 andH considered as a system are always focused in the plane of diaphragmi9. Turning of ring 29 varies the magnification of the eyepiece, but

the eyepiece is always in focus.

Since the objectiv lens system and the erect ing lens system are eachfixed, the diaphragm 46 may be fixed as to position and size. Thisdetermines the amount of light passing through the erecting lens systemand can be designed to produce an image of the highest quality. There isan important relationship between: (1) the air space between graticulei3 and lens l4, (2) the air space between lenses i l and I5, and (3) theposition and size of aperture in diaphragm 15. The invention affords afixed relationship. Furthermore the air space between lenses l6 and iiis fixed.

The change in magnification is secured by changing the air space betweenlenses l9 and 2!. The real field of view remains unchanged despitechange of magnification. The use of two lenses l6 and 26 allows bettercorrection of chromatic and spherical aberrations to be attained.

it is technically possible to apply the inventive principle using morethan the two ocular lenses i0 and H, but the simpler solution of theproblem 1;; rei erred.

What is claimed is:

1. A variable magnification erecting eyepiece for telescopes whichcomprises in combination a fixed erecting lenssystem having a fixedposterior focal plane; at least two optically alined ocular lenses;means supporting said ocular lenses for movement along their opticalaxes relatively to each other and relatively to said posterior focalplane; and means for imparting coordinated simultaneous movements tosaid supporting means to vary magnification while maintaining focus onsaid focal plane throughout movement of said ocular lenses along theiraxes.

2. The combination defined in claim 1 in which the erecting lens systemis constructed as a selfcontained subassembly including a tubularhousing in which the erecting lenses and at least one diaphragm arefixedly mounted.

3. The combination defined in claim 1 in which the erecting lens systemis constructed as a selfcontained subassembly including a tubularhousing in which the erecting lenses and two diaphragms are fixedlymounted, one of said diaphragms being between lenses and the other beingat the posterior focal plane of the system.

4. An recting telescope comprising a tube having an objective lenssystem and an erecting lens system alined therewith and each fixedlymounted within the tube and having a fixed posterior focal plane; and anocular lens system associated therewith and comprising at least twoaxially alined lenses, adjustable mounts supporting said lenses, one forguiding each of said lenses for movement relative to each other in axialdirections whereby the air space between said lenses may b varied tovary the magnification and means for imparting coordinated simultaneousmovements to said mounts to vary magnification while maintaining focuson said focal plane.

G'C'INTHER. F. E. LOECK.

References Cited in the file of this patent UNITED STATES PATENTS

